Flexible diaphragm for storage tank and its attaching means



April 9 H. w. WOODARD ETAL 3,028,040

FLEXIBLE DIAPHRAGM FOR STORAGE TANK AND ITS ATTACHING MEANS Filed July 31, 1959 2 Sheets-Sheet l April 3, 1962 w, wooD ETAL 3,028,040

FLEXIBLE DIAPHRAGM FOR STORAGE TANK AND ITS ATTACHING MEANS Filed July 31, 1959 2 Sheets-Sheet 2 United States atent D York Filed July 31, 1959, Ser. No. 830,815 8 Claims. (Cl. 22085) This invention relates to flexible diaphragms for placement inside storage tanks used for storing fluids and other flowable materials, and'to means for attaching the diaphragms in sealed relationship to the walls of the tanks. The invention is especially useful in storage tanks for fluids such, for example, as oils, gasoline, natural or artificial gas, and other fluid-hydrocarbons.

Storage tanks for fluid-hydrocarbons have heretofore used rigid, movable or floating roofs of relatively complicated, expensive construction and also utilized flexible diaphragms. The floating roof of known pan, or pontoon, or double deck type contacts and floats on the surface of the stored liquid, for example, hence is particularly susceptible to liquid leakage and vapor losses; whereas the flexible diaphragm in a tank with variable vapor space and fixed roof, may or may not contact and float on the surface of the stored liquid, but nevertheless rises and falls with fluctuations in the level of the liquid and is susceptible to some liquid and vapor leakage when leaky seams are present, although it prevents the rapid, free escape of the vapors given off by the liquid.

These rigid floating roofs and prior flexible diaphragms have been difficult to seal at their peripheries and generally permit objectionable losses by evaporation of the stored or contained fluid. Where prior flexible diaphragms have been used, difficulty has been experienced in positioning and securing the periphery of the diaphragm to the wall of the tank and in preventing premature failure, especially as by tearing and flexure fatigue failure at the peripheral marginal portion of the diaphragm.

The principle of the invention is a flexible, impervious, bag-like diaphragm or member with a beaded reinforced attaching band portion, and peripheral attaching means including a segmental member therefor adapted for place ment inside a storage tank, the diaphragm and said means, when in assembled sealed relationship within the storage tank, being capable of reducing product losses resulting from filling the tank and from vaporization and condensation of the stored or contained fluid, and capable of providing reduced fire hazard, and increased safety and control of odors.

Objects of the invention are to provide an improved flexible, impervious, bag-like diaphragm or member telescopically reversible on itself and adapted to be secured at a fixed elevation inside a storage tank; to provide im proved attaching means for securing the diaphragm in sealed relation to the wall of the tank; to provide for a removable type of attachment of the diaphragm to the tank with provision for the elimination of spaced fastener or bolt holes in the attaching band portion of the diaphragm; to provide for a clamped and sealed bead type of attachment of the diaphragm to the tank; to provide for the elimination of sewing, wicking and separation or opening in service of the seams of the flexible diaphragm; to provide for minimum porosity and permeability of the flexible diaphragm so as to eliminate weeping as by osmosis of gas, vapor and liquid through the diaphragm; to provide for avoiding sharp localized flexure of the attaching band portion of the diaphragm while the latter rises and falls with fluctuations in level of 3,028,040 Patented Apr. 3, 1962 the contained fluid; and to provide for simplicity of construction, convenience of manufacture and convenience of installation and attachment of the diaphragm and attaching means, and for effectiveness of operation.

These and other advantages of the invention will be apparent from the following description.

In the accompanying drawings which constitute a part of this specification and in which like numerals are employed throughout to designate like par-ts:

FIG. 1 is an elevational view showing a flexible baglike diaphragm mounted at a fixed elevation in a storage tank which diaphragm and its associated atataching means are constructed in accordance with and embody the invention, parts being broken away and in section;

FIG. 2 is an elevational view showing the flexible baglike diaphragm in a phase of its installation in the tank, parts being broken away and in section;

FIG. 3 is a cross-sectional view showing an attaching band portion of the diaphragm and radially outer and inner members or rings engaging and retaining the attaching band portion, broken lines indicating the diaphragm in its telescopically reversed position, parts being broken away;

FIG. 4 is a cross-sectional view showing a seam of the diaphragm in its as built uncured condition, parts being broken away;

FIG. 5 is a cross-sectional view of the diaphragm at its center region, parts being broken away;

FIG. 6 is a cross-sectional view showing a modification of the atataching band portion of the diaphragm.

Referring to the drawings, the numeral 16 designates a metal cylindrical storage tank or container having a bottom wall 11 supported by a concrete base 12 and having an upright, cylindrical side wall 13 and a fixed roof 14 with a free vent or bleeder 15 in communication with the space below the roof. The storage tank 10 is provided with a suitable inlet-outlet pipe 16 and control valve 17 in communication through the bottom wall 11 with the interior of the tank. The upright side wall 13 of the tank has a manhole or opening 18a and removable cover 18 adjacent the bottom wall 11. The roof 14 of the tank has a manhole or opening 19 at its center region closed by a detachable cover plate 20.

A flexible diaphragm 21 in the form of a bag-likemember, preferably a hemispherical member, of impervious flexible sheet material is detachably secured to the upright side wall 13 of the storage tank or container 10 at a fixed elevation above the bottom of the tank, as indicated at 22. The flexible bag-like diaphragm or member 21 is telescopically reversible on itself; hence is adapted to rise to its inflated position and configuration shown in full lines and to fall to its deflated position and configuration shown in broken lines in FIG. 1. The flexible bag-like diaphragm or member 21 is made of the said sheet material comprising an elastorner 23 resistant to fluid-hydrocarbons and fabric reinforcement 24 embedded in and united with the elastomer.

Good results have been obtained when the elastomer 23 comprises nitrile rubber, or polyester urethanes, or polyether urethanes, or polyamide urethanes, although not necessarily limited thereto, since other synthetic rubberlike material such, for example, as brominated butyl rubber, or neoprene (a polymer of chloroprene namely, 2- chlorobutadiene) may be utilized. The foregoing elastomeric materials are capable of being adhered to one another and to the fabric reinforcement and of being spread, coated or otherwise applied to the fabric reinforcement. They are also capable of undergoing under appropriate influences such as heat, pressure, and the action of a chemical substance, a change from an essentially plastic flowable condition to a relatively firmer or harder, more elastic and resilient condition.

Good results have been obtained when the fabric reinforcement 24 is a square-woven nylon fabric known commercially as Leno fabric (nylon being a polyamide of adipic acid and hexamethylenediamine). Other suitable strong, flexible fabrics and filamentary materials such as cotton, linen, and silk, or even fiberglass, or fine Wires may be utilized for some applications of the flexible diaphragm 21. A nylon fabric found to be satisfactory for a diaphragm tested experimentally in a 27 ft. diameter oil storage tank, for example, has the following characteristics:

Dry weight per sq. yd.2.4 ozs. 36 ends per inch 21 picks per inch .013 inch gauge Warp tensile strength-130 lbs. Filling tensile strengthl lbs.

This particular nylon fabric is coated on both sides with a suitable elastomer such as nitrile rubber so as to have a total thickness in the order of .050 inch, for example, to provide the desired impervious characteristics of the flexible bag-like diaphragm or member 2 Suitable patterns 25, 25 of the required configuration are utilized in forming the bag-like member 21. When such member or flexible diaphragm 21 has the hemispherical shape shown in the drawings, that is, the shape provided by a semi-circular surface of revolution about an axis or centrix, a plurality of gores 25, 25 (generally triangular configuration) of the impervious flexible sheet material 23, 24 are integrally and sealingly united one to the other by overlapped, longitudinally-extending seams 25a, 25a to provide the hemispherical member 21.

The gores 25, 25 forming the major part of the hemispherical member or flexible bag-like diaphragm 21 extend from a region adjacent the base of the member to the central region of the member where they are all united and closed by a circular center cap 26 of suitable fabric 24 coated on both sides with the elastomer material 23. The adjacent longitudinal margins and the narrow upper end margins of the adjacent gores 25, 25 and the circumferential margin of the center cap 26 are overlapped and initially cemented together. All the exposed cut fabric edges of the overlapped seams are overlapped and completely covered by thin all-elastomer cover strips 25b, 25b cemented in place to prevent, after cure, any possibility of wicking i.e. the passage of liquid or vapor through interstices in the cut ends of the threads of the fabric reinforcement 24 and to assure a strong fluid-tight seam or joint, as shown in FIGS. 4 and 5. A suitable liquid cement containing a suitable elastomer compatible and curable with the elastomer material 23 is used to initially adhere the overlapped, coated fabric margins one to the other and to adhere the elastomeric cover strips 25b, 25b to the fabric gores 25, 25 and the center cap 26 to facilitate subsequent curing and bonding of the seams under heat and pressure. This manner of joining the gores to one another and to the fabric center cap 26 is known as seaming the seam inside and outside and advantageously avoids the weakening and leakage effects of any sewing and objectionable needle holes in the fabric at the seams.

The bag-like diaphragm or hemispherical member 21 includes the feature of a continuous flexible attaching band portion 27 extending peripherally entirely about the open end or base of the member and provided with a flexible yieldable bead 28 formed'continuously along the free edge of the band portion, which bead is of substantially greater thickness than the remainder of the attaching band portion, such, for example, as approximately twice the maximum thickness of said remainder of the band portion. The head comprises a continuous annular flexible core 29' disposed within the bead, which core may be solid and of elastomeric material and circular-in-cross-section with a sectional diameter approximately half the thickness of the head as shown especially in FIG. 3, although not necessarily limited thereto, since the flexible core may be hollow tubing 29a of elastomeric material having a liquid-filled center space 29b as shown especially in FIG. 6, which liquid in the core may be glycerin, ethylene glycol, or other suitable anti-freeze solution.

The attaching band portion 27 includes at least one continuous annular layer 30 of suitable fabric 24 imbedded in elastomer 23 material, extending around the core 2? with the edges 31, 32 of the annular fabric layer 30 terminating remote from the core 29 with at least one 31 of the edges being located at the juncture of the attaching band portion 27 with the adjacent material of the hemispherical member 21 and integrally united with the said adjacent material i.e. the lower end margins of the gores 25, 25 shown especially in FIG. 3. The elastomer-coated fabric material of the annular layer 30 is united with the adjacent material of the hemispherical member by substantially overlapping and initially cementing and subsequently curing to the relatively wide lower end margins of the united gores 25, 25; and the cut ends of the threads in the respective fabric reinforcements in the layer 34} and the gores 25, 25 are entirely covered with suitable cover strips of all-elastomer material initially cemented in place and also cured to assure a fluid tight, secure connection and prevent wicking. This construction and arrangement of the attaching band portion 27 advantageously provides for the transmittal and distribution of the stresses, especially tension or pulling stresses, in the respective gores 25, 25 to the core 29 in the bead 28.

For purposes of effective sealing and increased strength together with compelling axial bending of the attaching band portion 27 about a relatively large radius of curvature immediately adjacent the attaching means so as to avoid sharp, localized, axial bending and flexure, the attaching band portion includes a plurality of continuous, annular, superimposed, spaced layers 30, 3'3, 34 of suitable fabric 24 enclosed within elastomer 23 material. These layers extend around the core 29 with the edges 31, 32 and 35, 36 and 37, 38, respectively, of the annular fabric layers 39, 33, 34 terminating different distances from the core 29 to provide in the attaching band portion a first annular portion 39 of substantially uniform thickness extending away from the head 28 to a second annular portion 40 of gradually decreasing thickness toward the juncture of the attaching band portion 27 with the adjacent material of the hemispherical member 21. This arrangement places the zone of maximum flexure and bending of the attaching band portion 27 at its thinnest area which is spaced and remote from the attaching means to thereby advantageously reduce abrasion and wear of the hemispherical member 21 at its region of attachment to the tank.

When the respective gores 25, the center cap 26 and the attaching band portion 27 are assembled, the fabric and elastomer material thereof are integrally united and cured by heat and pressure for maximum strength. All the cemented, overlapped seams with the cover strips 25b are similarly integrally united and cured, whereby the cover strips merge smoothly with the adjacent elastomer 23 coatings on the fabric 24 reinforcement as, for example, at the relatively wide, strong, overlapped seam joining the attaching band portion 27 to the adjacent material of the gores 275, 25 of the hemispherical member 21 as shown in FIG. 3.

In the cured condition, the attaching band portion 27 has a cross-sectional configuration in part of uniform thickness (for example, slightly more than half the crosssectional diameter of the bead 28) and in part of gradually tapered thickness as shown in FIG. 3, and has the bead 28 of circular cross-section and of greater cross-sectional diameter i.e. thickness than the thickness of the remainder of the attaching band portion 27. This bead 28 by virtue of the inclusion of the elastomer material 23 and the core 29, is not only flexible, but can be elastically deformed to a slightly reduced cross-sectional diameter, whereby the head is securely gripped and clamped by the attaching means, described hereinafter, so as to hold the hemispherical member 21 without resorting to the expedient of bolt holes and bolts extending through the attaching band portion 27. Such bolt holes are highly objectionable because they have unduly weakened and caused premature failure of the ordinary attaching marginal portion used heretofore in prior flexible diaphragms. A further advantage of this beaded attaching band portion 27 and the associated attaching means, is that the hemispherical member 241 can be much more quickly installed and removed as compared to the time required for the prior bolted-on or otherwise secured in place flexible diaphragm, and an effective fluid-tight seal is provided at the bead 28 and the immediately adjacent part of the uniform thickness portion 39 of the attaching band portion 27 despite axial flexure and bending of the attaching band portion as the hemispherical member rises and falls with fluctuations in the level of contained fluid or liquid.

The hemispherical member 21 at its center cap 26 may be provided with means for facilitating lifting the member to its upper position and temporarily retaining the member, while it is being attached to the wall of the storage tank. This means may consist of an eye bolt 41 secured to spaced, superimposed inner and outer metal plates 42, 43, respectively, between which plates are suitable impervious fabric stiffening discs 44, 45 and the fabric center cap 26 as shown in FIG. 5. This arrangement provides a seal at the eye bolt 41 and permits temporarily attaching the center cap 26 of the member 21 by means of the eye bolt, to a supporting cable 46 wound upon a winch 47 which is supported by a suitable structure 48. This structure 48 temporarily replaces the cover plate 26 in the roof 14 of the storage tank during the installation of the hemispherical member as shown in FIG. 2.

To facilitate telescopically reversible movement of the hemispherical member 21 and the desired axial bending and rolling movement of the attaching band portion 27, the member 21 has preferably a plurality of circumferentially spaced-apart weights 51, 51 (for example, about 40 lbs. each) held in place by a fabric support 49 and cord lacing 50. The Weights 51 are located adjacent but spaced from the attaching band portion 27 as shown in FIGS. 1 and 2.

The invention provides means to secure the attaching band portion 27 at a fixed elevation in the storage tank 10. For the particular embodiment shown in the drawings, the means comprises a continuous annular outer member or ring 52 for connection in sealed relation to the upright side wall 13 of the tank, a segmental annular inner member or ring 53 in concentric, radially aligned relation to the outer member 52, and means 54 extending externally of the attaching band portion 27 for attaching each individual arcuate segment of the inner member 53 to the outer member 52. The continuous outer member 52 and the segmental inner member 53 may each be made of metal such, for example, as structural (mild carbon) steel or other metal alloy having the desired stiffness and strength characteristics. However, for some applications the continuous annular outer member 52 need not be a separate member suitably attached to the wall 13, but instead the tank wall 13 itself can be constructed and arranged to function in place of and in substantially the same manner as the outer member 52 and so constitute an element of the attaching means. Also, for other applications the continuous outer member 52 can be seated against and welded or otherwise fastened directly to the tank wall 13 so as to be an integral part thereof. In the preferred construction, it is secured in radially spaced, sealed relation to the tank wall 13 and to this end may be fixedly attached as by welding the outer member 52 to a suitable metal, continuous, annular, bracket support 55 of inverted L-shaped cross section as shown in the drawings.

This bracket support 55 may be made initially segsegmental for insertion of the segments through the manhole 18a into the storage tank 10 after which the segments are interconnected and sealed end-to-end as by welding and caulking and the leg of the bracket 55 welded and caulked to the tank wall 13 in sealed relation thereto. The base of the bracket is welded and caulked continuously along the top of the continuous annular outer member 52, as shown especially in FIG. 3, to provide a seal at this location.

For convenience of manufacture and installation the outer member 52 may be made initially segmental to permit inserting the segments through the manhole 18a into the tank 10 and then securely welding the segments together in end-to-end sealed relation. The welded joints in the annular outer member 52 are further sealed by a suitable caulking compound applied after the Welding operation. Thus, the outer member 52 is formed continuous and annular and is connected, by virtue of the bracket support 55, in spaced, sealed relation to the upright wall 13 of the storage tank 10. This particular attachment of the outer member 52 facilitates convenience and accuracy of attaching the hemispherical member or flexible bag-like diaphragm 21 and the segmental annular inner member 53 to the continuous annular outer member 52 by operation from within the tank and below the hemispherical member or diaphragm 21 while the latter is temporarily held in its upper position as shown in FIG. 2.

The continuous annular outer member 52 has its radially inner side surface relieved radially outward as indicated at 56 in FIG. 3 to provide a continuous annular groove or radially relieved portion of arcuate cross-sectional configuration with a slightly less radius of curvature than that of the head. The depth of the groove 56 is about half its radius so as to receive only part of the head 28 of the attaching band portion 27. The circumferential edges of the groove 56 are rounded, but the remainder of said radially inner side surface of the outer member 52 can be unrelieved and straight as shown in FIG. 3, although not necessarily limited thereto, since for some applications it may be desirable to have that part of the said side surface above the groove 56 and bead 28 also radially relieved radially outward so as to be in increased diverging relation to the opposite adjacent side surface 58 of the segmental inner member 53. This latter arrangement provides increased V-shaped channel space above the head in which the attaching band portion 27 can flex and swing radially outward and inward during reversal of the wall of the hemispherical member 21 on itself.

The segmental annular inner member 53 has its radially outer side surface relieved radially inward as indicated at 57 in FIG. 3 to provide an annular groove or relieved portion 57 of arcuate cross-sectional configuration in register or radially aligned relationship with the radially relieved portion or groove 56 in the outer member 52 to receive part of the bead 28 of the attaching band portion 27. The groove 57 corresponds in radius of curvature and in depth to those of the opposed groove 56 and has rounded edges. The part of the said side surface of the inner member 53 below the bead 28 is not radially relieved. but that part of the said side surface above the head 28, indicated by the numeral 58, is radially relieved radially inward with this radially relieved portion 58 extending from the head to a rounded-in-cross-section circumferential edge portion 59 with a thickness approximately twice that of the attaching band portion 27 at its region above the bead 28. The radially relieved portion 58 may extend at an angle of 5 to the perpendicular and is in diverging relationship to the opposite adjacent side surface of the outer member 52 thereby defining l with the outer member a circumferentially continuous channel of substantially V-shaped cross-section open at its top or mouth and bottom and having its radially opposed side surfaces extending to the radially aligned, arcuate relieved portions or grooves 56, 57 in the outer 52 and inner 53 members.

This arrangement is advantageous to permit the desired axial bending and flexing and radial swin ing movement of the attaching band portion 27 within such open mouth channel and to permit bending the attaching band portion about the relatively large radius of curvature of the rounded circumferential edge portion 59 with maximum bending and flexure occurring remote from such edge portion 59 and at a zone where the attaching band portion 27 is of minimum thickness and stiffness. Thus, localized sharp flexure and axial bending about a very small radius of curvature at the inner member 53 of the attaching means are avoided by the invention, because such sharp flexure and bending produces rapid weakening and ultimate failure of the attaching band portion 27.

It will be noted that the part uniform thickness 39 and part tapering thickness 49 construction of the beaded edge attaching band portion 27 in co-action with the rounded circumferential edge portion 59 and the said open mouth, circumferential V-shaped channel between the outer and inner members 52 and 53, respectively, provide for controlled and gradual axial flexure and bending together with controlled radial swinging movement of the attaching band portion 27. This accommodates the reversal of the hemispherical member 21 on itself, while maintaining the strength of the member 21 at its attaching band portion 27 where maximum flexure and bending occurs in service during the rise and fall of the hemispherical member 21 with the level of the fluid contained in the storage tank 10.

An important feature of the invention is that when the annular outer 52 and inner 53 members are in the attached, substantially concentric, radially spaced relationship shown in FIG. 3, the surfaces of the radially aligned, opposed arcuate grooves 56, 57 partially bound at circular-in-section space with a diameter slightly less than the sectional diameter of the bead 28, whereby the head is elastically deformed and reduced in sectional diameter into contacting conformance and sealing relation with the arcuate surfaces of the grooves and effectively holds the diaphragm in place in the attaching means. Also, the radial width of the space between the opposed diverging side surfaces at the open bottom of the V- shaped channel is slightly less than the uniform thickness of portion 39 of the attaching band portion 27 at its narrow zone 39a immediately adjacent the bead 28 so as to elastically deform and reduce in thickness the portion 39 at its zone 39a into contacting, tightly sealed relationship to said side surfaces. Thus, a main or primary seal is produced at the zone 39a and at the upper part 23a of the head 28 of the attaching band portion 27, while a secondary seal is produced at the remainder of the head 23 in contact with the surfaces of the arcuate grooves 56, 57.

The segmental inner member 53 is attached individual segment by individual segment to the continuous outer member 52 by fastener means 54 with the individual segments arranged in end-to-end substantially abutting relationship circumferentially about the outer member 52 and with the joints between adjacent segments unsealed, caulking not being required. It is essential that welding the attached segments of the inner member 53 to one another be avoided, since the heat of welding will harm the elastomer materials comprising the hemispherical member or flexible bag-like diaphragm 21 including its attaching band portion 27. The individual segments of the inner member 53 can be independently detached whenever necessary as for replacing the hemispherical member 21.

The fastener means 54 which extends wholly externally of .the attaching :band portion 27, may consist of nut and bolt fasteners with the bolts adapted to extend through suitable circumferentially spaced openings in the continuous annular outer member 52 and in the respective individual segments of the inner member 53; consequently there are no circumferentially spaced holes in the attaching band portion 27 to weaken and cause premature failure thereof and sealing at the nut and bolt fasteners is not required. Preferably, each individual arcuate segment of the inner member 53 is provided with at least one bolt hole adjacent each of its ends for registering with corresponding bolt holes in the outer member 52. A suitable tubular metal spacer 60 is disposed between the outer member and the segmental inner member at each nut and bolt fastener 54 as shown especially in FIG. 3. The spacers 6G, 60 control the extent to which the bolt fasteners can be tightened and maintain the desired substantially uniform radial spacing of the outer 52 and inner 53 members, whereby the latter members tightly and securely clamp or grip the bead 28 between them without undue elastic deformation of the bead yet hold the hemispherical member 21 in attached sealed relation to the Wall 13 of the storage tank.

in the operation of the flexible bag-like or hemispherical member in its installed condition within the storage tank, such hemispherical member 21 is free to rise to its maximum height and hemispherical configuration as shown in full lines in FIG. I, and is also free to reverse on itself to assume the inverted generally hemispherical shape shown in broken lines in PEG. 1 and thereby accommodate various levels of contained fluid in the tank. The weights 51 which are optional with the user, facilitate the telescopic reversal of the hemispherical member 21 to the inverted generally hemispherical configuration. It will be noted that the movement of the hemispherical member in response to the level of contained fluid in the tank results in the hereinabove described radial swinging movement of the attaching band portion 27 and in the controlled, graduated, axial flexing and bending of the attaching band portion 27 about the rounded circumferential edge portion 59 of the inner member 53.

When the storage tank l0 contains crude oil or gasoline, for example, the hemispherical member or flexible baglike diaphragm 21, by virtue of the impervious character of its construction and its sealed attachment to the wall of the tank, may or may not float upon the surface of the contained liquid and may even by slightly suspended above the surface by the vapors emitted from the contained liquid. Neither the liquid nor the vapors can escape through the impervious wall of the flexible diaphragm 21 nor escape at the attachment thereof to the wall of the tank; consequently evaporation losses of the contained liquid and/ or vapor are greatly reduced. Such evaporation losses may amount, for example, from about 3 /2% to 10% per year, hence substantial reduction of such losses results in a substantial monetary saving each year.

Variations may be made without departing from the scope of the invention as it is defined in the following claims.

We claim:

1. A flexible diaphragm for placement inside a storage tank, said diaphragm comprising a bag-like member of impervious flexible sheet material comprising an elastomer resistant to fluid-hydrocarbons and fabric reinforcement imbedded in and united with said elastomer, the said bag-like member including a continuous flexible attaching band portion of greater thickness than the central region of the member extending peripherally entirely about the open end of said member and adapted to be clamped with-in said tank, the said band portion being provided with a flexible yieldable bead formed continuously along the free edge of the band portion and of substantially greater thickness than the remainder of said band portion with said bead comprising a continuous annular flexible core disposed within the bead, the said band portion including at least one continuous annular layer of fabric enclosed within elastomer material and extending around said core with the edges of the annular fabric layer terminating in said band portion at diiferent distances from said core with at least one of said edges being located at the juncture of said band portion with the adjacent material of said bag-like member and united with said adjacent material, the said juncture being spaced from the part of said band portion which is to be clamped, with the region between the latter and said juncture gradually tapering in thickness and increasing in flexibility toward said juncture thereby distributing flexing stresses in said band portion at said region thereof.

2. A flexible diaphragm for placement inside a storage tank, said diaphragm comprising a bag-like member of impervious flexible sheet material comprising an elastomer resistant to fluid-hydrocarbons and fabric reinforcement imbedded in and united With said elastomer, the said bag-like member including a continuous flexible attaching band portion of greater thickness than the central region of said member extending peripherally entirely about the open end of said member and adapted to be clamped within said tank, the said band portion being provided with a flexible yieldable bead formed continuously along the free edge of the band portion and of substantially greater thickness than the remainder of said band portion with said bead comprising a continuous annular flexible core of deformable material disposed within the head, the said band portion including a plurality of annularly continuous superimposed layers of elastomer covered fabric extending around said core with the edges of the said layers terminating in said band portion at diiferent distances from said core to provide in said band portion an annular portion of gradually decreasing thickness but increasing flexibility toward the juncture of said band portion with the adjacent material of said bag-like member, said annular portion extending between the part of said band portion which is to be clamped, and said juncture thereby distributing flexing stresses beyond the clamped part of said band portion.

3. A flexible diaphragm for placement inside a storage tank, said diaphragm comprising a hemispherical member of impervious flexible sheet material comprising an elastomer resistant to fluid-hydrocarbons and woven fabric reinforcement imbedded in and united with said elastomer, the said hemispherical member including a continuous imperforate flexible attaching band portion of greater thickness than that of the central portion of said member which band portion extends circumferentially entirely about the open end of said member and is adapted to be clamped within the tank, the said band portion being provided with a flexible yieldable bead of generally rounded shape in cross-section formed continuously along the free edge of the band portion and of substantially greater thickness than the remainder of said band portion with said bead comprising an annularly continuous flexible core including elastomer material disposed centrally Within the bead, the said band portion including a plurality of annularly continuous superimposed layers of woven fabric enclosed within elastomer material and extending around said core with the edges of the said layers terminating in said band portion at different distances from said core to provide in said band portion a first annular portion of substantially uniform thickness which is to be clamped, extending away from said bead to a second annular portion of gradually decreasing thickness but increasing flexibility toward the juncture of said band portion with the adjacent material of said hemispherical member thereby distributing flexing stresses beyond the clamped first portion of said band portion.

4. A flexible diaphragm assembly for placement inside a storage tank, said diaphragm assembly comprising a baglike member of impervious flexible sheet material comprising an elastomer resistant to fluid-hydrocarbons and fabric reinforcement imbedded in and united with said elastomer, the said bag-like member including a continuous flexible attaching band portion of greater thickness than the central portion of said diaphragm with the said band portion extending peripherally entirely about the open end of said member and provided with a flexible yieldable bead formed continuously along the free edge of the band portion and of substantially greater thickness than the remainder of said band portion with said bead comprising a continuous annular flexible core disposed within the head, the said band portion including at least one continuous annular layer of fabric enclosed within elastomer material and extending around said core with the edges of the said layer terminating in said band portion at different distances from said core with at least one of said edges being located at the juncture of said band portion with the adjacent material of said bag-like member and united with said adjacent material, and means to secure and clamp said attaching band portion at a fixed elevation in said tank comprising a plurality of segmental arcuate members for disposition in substantially abutting end-to-end relationship, said members each having its radially outer side surface relieved radially inwardly with the relieved portion extending to a rounded-in-cross-section circumferential edge portion for accommodation of said head and part of said attaching band portion thereby permitting clamping of the bead of the diaphragm and bending of the attaching band portion about said edge portion, and means extending externally of said attaching band portion for separately attaching each individual segmental arcuate member to said tank.

5. A flexible diaphragm assembly for placement inside a storage tank, said diaphragm assembly comprising a bag-like member of impervious flexible sheet material comprising an elastomer resistant to fluid-hydrocarbons and fabric reinforcement imbedded in and united with said elastomer, the said bag-like member including a continuous imperforate flexible attaching band portion of greater thickness than the central portion of said diaphragm with the said band portion extending peripherally entirely about the open end of said member and provided with a flexible yieldable bead formed continuously along the free edge of the band portion and of substantially greater thickness than the remainder of said b and portion with said head comprising a con-tinuous annular flexible core disposed within the head, the said band portion including at least one continuous annular layer of fabric enclosed within elastomer material and extending around said core with the edges of the said layer terminating in said band portion at different distances from said core with at least one of said edges being located at the juncture of said band portion with the adjacent material of said bag-like member and united with said adjacent material, and means to secure the said attaching band portion at a fixed elevation in said tank comprising a continuous peripherally annular outer member for connection in sealed relation to the wall of the tank, the radially inner side surface of said outer member being relieved radially outwardly, a plurality of segmental arcuate inner members arranged in substantially abutting end-to-end relationship providing an inner ring, said inner members each having its radially outer side surface relieved radially inwardly in spaced register with the relieved portion of said outer member to receive therebetween said bead, each of said segmental members also having a rounded-in-cross-section circurnferential edge portion to permit bending thereover of the attaching band portion of the diaphragm, and means extending externally of said attaching band portion for separately attaching each individual segmental inner member to said annular outer member with the bead of the diaphragm clamped therebetween.

6. Means for storing liquids comprising a tank having a generally circular inner sidewall, a generally hemispherically shaped flexible diaphragm including a thickened attaching band portion along the periphery of the diaphragm with a relatively thicker peripherally extending head at the edge of said band portion, and means for connecting said diaphragm at a fixed elevation to the inner wall of the tank to provide therein a chamber of variable capacity, the said connecting means comprising a continuous outer ring member mounted in fluid-tight relationship on the inner wall of the tank, a plurality of segmental clamping inner ring members disposed end-toend peripherally in adjacent radially spaced aligned relation to said outer ring member with adjacent radially opposed side surfaces of the outer and inner ring members radially relieved in a manner providing continuous circumferentially extending radially aligned grooves each of generally half-round shape in cross section for receiving and retaining the bead of the said attaching band portion, a part of the radially relieved side surface of each of said inner ring members extending from the grooye therein in diverging relationship to said radially opposed side surface of the outer ring member to accommodate a part of the attaching band portion, said inner ring members having a rounded-in-cross section outer edge portion to permit bending thereabout of the said band portion, and means extending externally of said attaching band portion for separately attaching each individual inner ring member to said outer ring member.

7. Means for storing liquids comprising a tank having a generally circular inner sidewall, a generally hemispherically shaped flexible diaphragm including a thickened attaching band portion along the periphery of the diaphragm with a relatively thicker peripherally extending bead at the edge of said band, and means for connecting said diaphragm at a fixed elevation to the inner wall of the tank to provide therein a chamber of variable capacity, the said connecting means comprising a continuous outer ring member mounted in fluid-tight relationship on the inner wall of the tank, a segmental inner ring member disposed in radially spaced aligned relation to said outer ring member with adjacent radially opposed side surfaces of the outer and inner ring members radially relieved in a manner providing continuous circumferentially extending radially aligned grooves receiving and retaining therein the said head of the attaching band portion, the radially relieved portion of said segmental inner ring member extending from the groove therein in diverging relation to said radially opposed side surface of the outer ring member and defining therewith a continuous open-mouthed circumferential channel to accommodate therein a part of the attaching band portion, the said inner ring member having a rounded-in-cross section circumferential outer edge portion to permit bending thereabout of the said attaching band portion, and means extending externally of said attaching band portion for separably attaching each individual segment of the inner ring member to said outer ring member.

8. Means for connecting a beaded attaching band portion of a flexible bag-like diaphragm at a fixed elevation on the inner wall of a storage tank to provide in the latter a chamber of variable capacity, the said connecting means comprising a continuous outer ring member adapted to be mounted in fluid-tight relationship on the inner wall of the storage tank, a segmental inner ring member disposed in adjacent spaced radially aligned relation to said outer ring member with adjacent radially opposed side surfaces of the outer and inner ring members spaced from the wall of the tank and radially relieved in a manner providing continuous circumferentially extending radially aligned grooves adapted for receiving and retaining therein a flexible yieldable bead of the diaphragm, the radially relieved portion of said segmental inner ring member extending from the groove therein in diverging relation to said radially opposed side surface of the outer ring member and defining therewith a continuous open-mouthed circumferential channel to accommodate therein a part of the attaching band portion, the said segmental inner ring member having a rounded-in-cross section circumferentially extending edge portion at the mouth of said channel to permit bending thereabout of the said attaching band portion, and means extending externally of said band separably attaching each individual segment of said inner ring to said outer ring member.

References Cited in the file of this patent UNITED STATES PATENTS 1,669,183 Wilson May 8, 1928 2,578,090 Plummer Dec. 11, 1951 2,647,657 Krupp Aug. 4, 1953 2,731,334 Wissmiller et al Jan. 17, 1956 2,740,549 Graham et a1 Apr. 3, 1956 2,948,432 Bodley Aug. 9, 1960 FOREIGN PATENTS 682,016 France Feb. 16, 1930 n the above numbered patrs Patent should read as corrected below.

Column l0 line 55, for "continuous peripherally" read peripherally continuous column 11, line 17, for "grooye" read groove Signed and sealed this 13th day of November 1962.

TSEAL) lttest:

ERNEST W. SWIDER DAVID L. LADD nesting Officer Commissioner of Patents 

